[Note: This post was updated on Dec. 23, 2020.]
Q: In an article about the Gilroy, CA, shooting, the NY Times says investigators “also are continuing to scrub various electronic devices and trying to learn if he had any help carrying out the shooting.” Isn’t this an incorrect use of “scrub,” which I’d always understood to mean, in this context, to make data unrecoverable?
A: No, that’s not the only definition of “scrub” in digital technology. When used in technical senses, the verb “scrub” can mean either (1) to clean or erase, or (2) to examine by fast-forwarding or rewinding.
These uses of “scrub” are well known to people familiar with digital and audio/video technologies. They’re becoming more common as time goes by, though the second one is rather new.
However, in searching the ten standard British and American dictionaries we usually consult, we were surprised to find that only two have caught up to these senses of the word.
For instance, The American Heritage Dictionary of the English Language has definitions having to do with cleaning and erasing; here they are, along with examples:
“a. To maintain the integrity of by finding and correcting errors: software that automatically scrubs stored data.
“b. To erase in such a way as to render unrecoverable: scrubbed the laptop’s hard drive to destroy incriminating evidence.”
And Dictionary.com has this in the audio/video sense: “to fast-forward or rewind in an audio or video file by dragging the progress marker forward or backward across the timeline bar: Scrub forward through the pregame and start playback from the kickoff.”
Some older, specialized reference books have limited definitions too, perhaps because fast-forwarding and rewinding technology was less developed at the time. Here are examples of the verb as used in computer science:
“To examine a large amount of data and eliminate duplicate or unneeded items” (McGraw-Hill Dictionary of Scientific & Technical Terms, 2003). “To wipe information off a disk or remove data from store” (Simon Collin’s Dictionary of Computing, 2009).
In its nontechnical usage, “scrub” has similar senses: (1) to vigorously clean something by rubbing, as in “he scrubbed the kitchen floor,” and (2) to cancel or eliminate, as in “the launch was scrubbed” or “his horse was scrubbed from the race.”
The Oxford English Dictionary, an etymological dictionary based on historical evidence, has no entries for computer senses of “scrub,” at least not yet. As for less technical uses, the OED describes the verb as Germanic in origin and “of obscure history.”
The verb was first recorded in Middle English writing in the 1300s, when it meant to curry-comb a horse, a sense that may have come from Middle Low German or Middle Dutch terms for scraping or scrubbing.
In its modern sense—to clean by hard rubbing—“the word may perhaps have been re-imported from Dutch as a nautical term,” the OED suggests.
This current sense of “scrub” was first recorded in the 16th century, at a time when Holland was a major naval power and many Dutch nautical words came into English. In those days, the English word meant “to clean (esp. a floor, wood, etc.) by rubbing with a hard brush and water.”
However, the earliest OED example, from 1595, uses the term figuratively. It’s from a contemporary account of Sir Francis Drake’s final, disastrous expedition against Spain in the West Indies:
“If part of our companie had been sent thither upon our first arrival at Rio de la Hacha, doubtles we had done much goode, but now they [the Spaniards] had scrube it very bare.” (From Sir Francis Drake His Voyage, 1595, a contemporary narrative written by a passenger, Thomas Maynarde. In December 1595, Drake’s men landed at the city only to find that the Spanish had “scrubbed” it bare—that is, removed everything of value.)
The dictionary’s earliest use of “scrub” meaning to cancel or eliminate is from the early 19th century, and is found in the private writings of Sir Walter Scott:
“If I were alone, I could scrub it [a visit to London], but there is no doing that with Anne” (a diary entry written March 22, 1828, and first published in The Journal of Sir Walter Scott, 1941).
The dictionary defines the word in this sense as “to cancel, scrap, call off; to eliminate, erase; to reject, dismiss.” It adds that this usage was “reinforced by the popularity of the expression amongst servicemen in the war of 1939–45.”
Oxford includes several WWII uses, both British and American, including this enlightening passage from a letter to the editor of the Spectator. The letter, from a British naval officer, ran on May 25, 1945, in response to a review of a book on air force slang:
“The author can possibly justify the inclusion of the term ‘scrub,’ meaning ‘to cancel,’ in a collection of R.A.F. slang. The expression is in common use in the Royal Navy and has been for many generations. It derives from the days when all signals and orders were written on a slate. When the signals were cancelled or orders executed, the words on the slate were ‘scrubbed out’ or, equally correctly ‘washed out.’ ”
[Note: Two readers called our attention to the increasingly common fast-forward and rewind sense of “scrub.” As one commented: “Audio and video scrubbing is moving quickly through a recording (fast-forward or fast-rewind) while the recording plays in order to find a specific spot in the recording. It does not seem like a stretch to me to go from searching an audio or video recording for something specific to searching data recorded on a computer drive for something specific.”]